The signs which are used to express different whorls, number of floral leaves, their arrangements symmetry, sexuality etc. of the flower are said to be floral formula Letters and signs used in floral formula.

Rules of writing floral formula:

(i) Floral formula is started with the sign of sexuality of the flower and it will be followed gradually by sign of symmetry, bract, calyx, corolla, androecium and finally gynoecium.

(ii) The number of units of each whorl can be expressed by putting number just beside the whorl The units are united when they are connected with brackets, but are not connected with bracket when the floral leaves of each whorl are free.

(iii) When there is a line on the top of two whorls, remaining whorls are said to be united.

(iv) By putting a line on or below the gynoecium means inferior or superior respectively.